Scroll apparatus for fluid compression or expansion are typically comprised of two upstanding interfitting involute spirodal wraps which are generated about respective axes. Each respective involute wrap is mounted upon an end plate and has a tip disposed in contact or near-contact with the end plate of the other respective scroll wrap. Each scroll wrap further has flank surfaces which adjoin in moving line contact, or rear contact, the flank surfaces of the other respective scroll wrap to form a plurality of moving chambers. Depending upon the relative orbital motion of the scroll wraps, the chambers move from the radial exterior end of the scroll wraps to the radially interior ends of the scroll wraps for fluid compression, or from the radially interior end of the respective scroll wraps for fluid expansion. The scroll wraps, to accomplish the formation of the chambers, are put in relative orbital motion by a drive mechanism which constrains the scrolls to non-rotational motion. The general principles of scroll wrap generation and operation are discussed in numerous patents, such as U.S. Pat. No. 801,182.
Numerous attempts have been made to develop co-rotational scroll apparatus. Such apparatus provides for concurrent rotary motion of both scroll wraps on parallel, offset axis to generate the requisite orbital motion between the respective scroll wrap elements. However, most commercially successful scroll apparatus to date have been of the fixed scroll-orbiting scroll type due to various difficulties in achieving success with co-rotating scroll apparatus.
Typically, a large number of rotary bearings are required in a co-rotational scroll apparatus, which decreases the reliability and efficiency of the machine. Furthermore, the typical co-rotating scroll apparatus have required a thrust bearing acting upon each of the scroll endplates to prevent axial scroll separation, thus substantially increasing the power requirements of the machine as well as substantially reducing the reliability of the machine.
Furthermore, it has been determined that the rotating action of the scroll elements within the apparatus tends to induce a concurrent swirling or circular motion of the fluid entering the scroll apparatus to be compressed or pumped. This swirling action of the fluid Is undesirable for several reasons. First, the efficiency of the scroll apparatus is lowered due to the difficulty of drawing the moving fluid into the scroll elements. Secondly, additional power must be supplied to rotate both the scroll elements and the incoming fluid, increasing the size of the drive means for the scroll apparatus and hence increasing both the initial and operating cost. Thirdly, lubricant, which would desirably lubricate the scroll elements is typically suspended in the incoming fluid, is precipitated out of the incoming fluid. This has the dual effects of providing little or no lubricant to the scroll elements and of potentially filling the space in which the scroll elements operate with lubricant or lubricant foam. In either case, unnecessary wear and damage to the scroll apparatus may result.
Therefore it is an object of the present invention to provide such a co-rotating scroll apparatus as will provide the highest possible efficiency while utilizing the least amount of power and therefore having the lowest power and least costly drive means.
Yet another object of the present invention is to provide a co-rotating scroll apparatus as will permit the suitable flow of lubricant.
It is still a further object of the present invention to provide such a co-rotating scroll apparatus which is of simple construction and high operating reliability.
It is yet a further object of the present invention to provide a co-rotating scroll apparatus which is relatively axially compliant and not susceptible to damage in operation.
Finally, it is an object of the present invention to provide such a scroll apparatus as is suitable for and is relatively inexpensive in mass production.